1. Field of the Invention
This invention relates to a distributor rotor for use with an after market distributor cap that is secured to a computer controlled electronic distributor that distributes voltages to spark plugs in internal combustion engines by a distributor cap adapter. More particularly, the invention relates to an injection molded distributor rotor having a stainless steel spring contact and a metallic contact overlaid the stainless steel spring contact for relocating the critical electrical contacts to a desired location when used with the after market distributor cap.
2. Discussion of Related Art
Conventional computer controlled electronic distributors distribute high voltage to spark plugs in various conventional internal combustion engines. After market distributor caps are commercially available and used throughout the automotive after market industry. However, when the conventional computer controlled electronic distributors attempt to distribute a secondary high voltage to an appropriate cylinder at the correct time, a high ignition load circumstance develops for either a secondary wire or sparkplug.
At this point, the secondary high voltage spark can be directed to an incorrect distributor cap terminal, i.e., a wrong cylinder. Furthermore, even though a correct cylinder terminal is closer in distance, the correct cylinder terminal may have a higher load that requires more energy to fire the sparkplug than an adjacent terminal which is longer in distance but lower in load requirements. The wrong cylinder is known in the art as a low demand cylinder that is commonly positioned near fresh fuel and air in the beginning of a compression stroke.
When the high voltage spark goes to the low demand cylinder, a pre-ignition event commonly called cross fire results. Cross fire is defined as firing the wrong cylinder at the wrong time during which an attempt is made to stop a corresponding piston from compressing any further, but cannot occur successfully because of the momentum of the engine assembly. Also, a sudden rise in the pressure and temperature of the conventional internal combustion engine can be approximately 4 to 20 times higher than the engine is designed for regular combustion.
Furthermore, the weakest components of the combustion cycle will be sought out during cross fire. As the piston is usually the weakest component, typical results are a broken center portion of the piston, which results in the complete loss of any combustion processes from taking place, that is, no power is generated. Additionally, crankcase oil will be exposed to intake and exhaust systems through valves, wherein pieces of the piston can contaminate the intake and exhaust systems as well as the crankcase oil.
As a result, damage will extend throughout the conventional internal combustion engine by foreign particles being transported to other areas of the engine. For example, the piston will typically scuff the cylinder wall because of the high heat, thereby ruining the cylinder itself. Also, any one of the connecting rod, connecting rod bearing, and the crankshaft of the engine can suffer damage due to the high pressures they have to endure. Accordingly, the conventional internal combustion engine can be severely damaged.
Injection molded rotors are known in the art. For example, U.S. Pat. No. 1,385,625 to Kent discloses a distributor having a member 10 with a recess 9 that is engaged by an upper end 8 of a cam shaft 7. The member 10 has a transversely extending rib at the bottom of the recess 9 that is integral with the member 10 and engages an offset slot in the upper end 8 of the cam shaft 7, whereby the shaft 7 rotates the member 10. A resilient contact 12 made of spring steel or the like is carried by the member 10 and secured at an end adjacent the outer end of the member 10 and extends substantially radial toward the center and upwardly away therefrom, whereby the free end of the contact 12 is spaced from the member 10 and resists movement toward the member.
The contact 12 may be secured to the member 10 in any suitable way. In the example illustrated in FIG. 2, the contact 12 is held by a screw 13 threaded into the metallic bushing or insert 14 molded into the member 10. The same screw may secure a metallic brush 15 to the member 10, whereby the contact 12 and member 15 are in electrical connection with each other. An upstanding lug 20 is integrally molded with the member 10 and has an undercut 21.
The lug 20 and undercut 21 are so positioned that the free end of the spring contact 12 extends into the undercut 21 and a lip 22 limiting the distance away from the member 10 to which the contact 12 may spring. By the above-described structure, the distance to which the free end of the contact 12 may spring away from the member 10 is limited, yet that contact may yield toward the distributor member 10 while coacting with the terminal 17 carried by the cap 3. The contact 12 cannot spring away from the member 10 to such a distance as might or would interfere with the attachment of the cap 3 to the base 1.
In another example, U.S. Pat. No. 4,030,466 to Lace discloses a synchronous rotor indexing mechanism having an insulating rotor 10. The rotor 10 has a movable contact 11 mounted thereon which can be advanced or retarded, relative a terminal 12. The terminal 12 is a contact inside the housing (not shown) of the distributor (also not shown) which connects to a particular spark plug.
A centrifugal force acting on a weight 13, movably mounted on a shaft 19, causes the weight to moved towards the perimeter of the rotor 10. Two corners 14 of the weight 13 press against the side surface 15 of the contact 11. The contact 11 is pivoted at a pivot point 16, thus, as the weight 13 moves outwardly along the shaft 19, the outward end of the contact 11 is caused to advance relative to the rotor 10 and rotor shaft.
A spring 17 imposes the outward motion of the weight 13 and provides a restoring force for the weight 13 and the contact 11. The shoulders 18 of the rotor are designed to limit the travel of the contact 11, while portions 20 of the rotor serve as stops for the weight 13 and as a base for the shaft 19 and spring 17. The high voltage connection is made by means of a sliding contact engaged with inner most end 21 of the contact 11.
FIG. 5 illustrates an alternative embodiment of the rotor 10 in which the contact member 32 combines the functions of electrical contact, weight, and restoring spring. The contact arm is fixedly mounted at its inner most end 21 to the rotor and has a rod portion connecting the more massive portion at the outmost end. The center of gravity is angularly displaced from the rod portion. As the engine velocity increases, centrifugal force will tend to advance the outmost end of the contact 32 at the bending movement.
FIG. 9 shows another embodiment of the rotor 10 wherein the contact member 44 is eccentrically mounted at and pivoted about a point 45. A vertical portion 46 of the resilient high voltage 12 also provides a restoring force.
In U.S. Pat. No. 4,036,197 to Beshore, an automotive ignition distributor conversion means having an ignition timing motor 22 with an upper transverse arm 24 that terminates at a high tension wiper contact 26 is disclosed. The inner end of the contact 26 at the high tension rotor arm 24 engages a contact button (not shown) on the inner side of the distributor cap 28 which is electrically connected to a high tension socket 34. As the rotor 22 turns, the outer end of the rotor contact 26 wipes across contact buttons (not shown) on the inside of the distributor cap 28 electrically connected to the spark plug cable sockets 32 to apply the high tension voltage to the spark plug in the proper firing order. The high tension motor 22 is mounted on the upper end of the motor shaft 18 of the distributor body 16.
U.S. Pat. No. 4,077,378 Okumura discloses a distributor with a rotor 1 fixed to an upper portion of a shaft of the distributor to rotate in response to the rotation of crank shaft. The rotor 1 and cap 2 have a rotor electrode 3 made of brass in the plurality of electrodes 4 made of aluminum. The rotor electrode 3 faces to the side of electrodes 4 and has a thin metal member 5 made of stainless steel, which is secured thereto by spot welding 6. The metal member 5 has a width extending in the rotational direction of the rotor electrode 3 to cover all the spark timings. The stainless steel member 5 can be steel, aluminum, brass or copper, and fixed by soldering or rivets.
U.S. Pat. No. 4,096,840 to Jordan discloses an ignition distributor having a rotor member 38 made of a dielectric material, such as a plastic or the like, frictionally held in position and keyed in an appropriate angular position relative to the shaft 16. A flat spring 42 is supported by the rotor 38 wherein the end of the flat spring is consistently in engagement with the projecting end of the terminal 24 of the cap 18. The other end of the spring is attached to a projecting end of the rotor 38.
As such, although injection molded rotors appear to be known, none of the above-listed and/or described references disclose an injection molded rotor designed to eliminate the possibility of a high demand situation from occurring. Furthermore, because eliminating the high demand situation from occurring is difficult to accomplish given that maintenance intervals, defective parts, equipment abuse, and operating conditions are all but impossible to monitor as a primary supplier of conventional internal combustion engines having distributors, recent manufacturers have eliminated the distributor from the conventional engines altogether. Accordingly, there is a need for a solution for conventional engines still using the conventional controlled electronic distributor.